/*
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 *
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/*
 *
 *
 *
 *
 *
 * Written by Doug Lea with assistance from members of JCP JSR-166
 * Expert Group and released to the public domain, as explained at
 * http://creativecommons.org/publicdomain/zero/1.0/
 */

package java.util.concurrent;

import java.io.ObjectStreamField;
import java.util.Random;
import java.util.Spliterator;
import java.util.concurrent.atomic.AtomicInteger;
import java.util.concurrent.atomic.AtomicLong;
import java.util.function.DoubleConsumer;
import java.util.function.IntConsumer;
import java.util.function.LongConsumer;
import java.util.stream.DoubleStream;
import java.util.stream.IntStream;
import java.util.stream.LongStream;
import java.util.stream.StreamSupport;

/**
 * A random number generator isolated to the current thread.  Like the
 * global {@link java.util.Random} generator used by the {@link
 * java.lang.Math} class, a {@code ThreadLocalRandom} is initialized
 * with an internally generated seed that may not otherwise be
 * modified. When applicable, use of {@code ThreadLocalRandom} rather
 * than shared {@code Random} objects in concurrent programs will
 * typically encounter much less overhead and contention.  Use of
 * {@code ThreadLocalRandom} is particularly appropriate when multiple
 * tasks (for example, each a {@link ForkJoinTask}) use random numbers
 * in parallel in thread pools.
 *
 * <p>Usages of this class should typically be of the form:
 * {@code ThreadLocalRandom.current().nextX(...)} (where
 * {@code X} is {@code Int}, {@code Long}, etc).
 * When all usages are of this form, it is never possible to
 * accidently share a {@code ThreadLocalRandom} across multiple threads.
 *
 * <p>This class also provides additional commonly used bounded random
 * generation methods.
 *
 * <p>Instances of {@code ThreadLocalRandom} are not cryptographically
 * secure.  Consider instead using {@link java.security.SecureRandom}
 * in security-sensitive applications. Additionally,
 * default-constructed instances do not use a cryptographically random
 * seed unless the {@linkplain System#getProperty system property}
 * {@code java.util.secureRandomSeed} is set to {@code true}.
 *
 * @author Doug Lea
 * @since 1.7
 */
public class ThreadLocalRandom extends Random {
    /*
     * This class implements the java.util.Random API (and subclasses
     * Random) using a single static instance that accesses random
     * number state held in class Thread (primarily, field
     * threadLocalRandomSeed). In doing so, it also provides a home
     * for managing package-private utilities that rely on exactly the
     * same state as needed to maintain the ThreadLocalRandom
     * instances. We leverage the need for an initialization flag
     * field to also use it as a "probe" -- a self-adjusting thread
     * hash used for contention avoidance, as well as a secondary
     * simpler (xorShift) random seed that is conservatively used to
     * avoid otherwise surprising users by hijacking the
     * ThreadLocalRandom sequence.  The dual use is a marriage of
     * convenience, but is a simple and efficient way of reducing
     * application-level overhead and footprint of most concurrent
     * programs.
     *
     * Even though this class subclasses java.util.Random, it uses the
     * same basic algorithm as java.util.SplittableRandom.  (See its
     * internal documentation for explanations, which are not repeated
     * here.)  Because ThreadLocalRandoms are not splittable
     * though, we use only a single 64bit gamma.
     *
     * Because this class is in a different package than class Thread,
     * field access methods use Unsafe to bypass access control rules.
     * To conform to the requirements of the Random superclass
     * constructor, the common static ThreadLocalRandom maintains an
     * "initialized" field for the sake of rejecting user calls to
     * setSeed while still allowing a call from constructor.  Note
     * that serialization is completely unnecessary because there is
     * only a static singleton.  But we generate a serial form
     * containing "rnd" and "initialized" fields to ensure
     * compatibility across versions.
     *
     * Implementations of non-core methods are mostly the same as in
     * SplittableRandom, that were in part derived from a previous
     * version of this class.
     *
     * The nextLocalGaussian ThreadLocal supports the very rarely used
     * nextGaussian method by providing a holder for the second of a
     * pair of them. As is true for the base class version of this
     * method, this time/space tradeoff is probably never worthwhile,
     * but we provide identical statistical properties.
     */

  /**
   * Generates per-thread initialization/probe field
   */
  private static final AtomicInteger probeGenerator =
      new AtomicInteger();

  /**
   * The next seed for default constructors.
   */
  private static final AtomicLong seeder = new AtomicLong(initialSeed());

  private static long initialSeed() {
    String pp = java.security.AccessController.doPrivileged(
        new sun.security.action.GetPropertyAction(
            "java.util.secureRandomSeed"));
    if (pp != null && pp.equalsIgnoreCase("true")) {
      byte[] seedBytes = java.security.SecureRandom.getSeed(8);
      long s = (long) (seedBytes[0]) & 0xffL;
      for (int i = 1; i < 8; ++i) {
        s = (s << 8) | ((long) (seedBytes[i]) & 0xffL);
      }
      return s;
    }
    return (mix64(System.currentTimeMillis()) ^
        mix64(System.nanoTime()));
  }

  /**
   * The seed increment
   */
  private static final long GAMMA = 0x9e3779b97f4a7c15L;

  /**
   * The increment for generating probe values
   */
  private static final int PROBE_INCREMENT = 0x9e3779b9;

  /**
   * The increment of seeder per new instance
   */
  private static final long SEEDER_INCREMENT = 0xbb67ae8584caa73bL;

  // Constants from SplittableRandom
  private static final double DOUBLE_UNIT = 0x1.0p-53;  // 1.0  / (1L << 53)
  private static final float FLOAT_UNIT = 0x1.0p-24f; // 1.0f / (1 << 24)

  /**
   * Rarely-used holder for the second of a pair of Gaussians
   */
  private static final ThreadLocal<Double> nextLocalGaussian =
      new ThreadLocal<Double>();

  private static long mix64(long z) {
    z = (z ^ (z >>> 33)) * 0xff51afd7ed558ccdL;
    z = (z ^ (z >>> 33)) * 0xc4ceb9fe1a85ec53L;
    return z ^ (z >>> 33);
  }

  private static int mix32(long z) {
    z = (z ^ (z >>> 33)) * 0xff51afd7ed558ccdL;
    return (int) (((z ^ (z >>> 33)) * 0xc4ceb9fe1a85ec53L) >>> 32);
  }

  /**
   * Field used only during singleton initialization.
   * True when constructor completes.
   */
  boolean initialized;

  /**
   * Constructor used only for static singleton
   */
  private ThreadLocalRandom() {
    initialized = true; // false during super() call
  }

  /**
   * The common ThreadLocalRandom
   */
  static final ThreadLocalRandom instance = new ThreadLocalRandom();

  /**
   * Initialize Thread fields for the current thread.  Called only
   * when Thread.threadLocalRandomProbe is zero, indicating that a
   * thread local seed value needs to be generated. Note that even
   * though the initialization is purely thread-local, we need to
   * rely on (static) atomic generators to initialize the values.
   */
  static final void localInit() {
    int p = probeGenerator.addAndGet(PROBE_INCREMENT);
    int probe = (p == 0) ? 1 : p; // skip 0
    long seed = mix64(seeder.getAndAdd(SEEDER_INCREMENT));
    Thread t = Thread.currentThread();
    UNSAFE.putLong(t, SEED, seed);
    UNSAFE.putInt(t, PROBE, probe);
  }

  /**
   * Returns the current thread's {@code ThreadLocalRandom}.
   *
   * @return the current thread's {@code ThreadLocalRandom}
   */
  public static ThreadLocalRandom current() {
    if (UNSAFE.getInt(Thread.currentThread(), PROBE) == 0) {
      localInit();
    }
    return instance;
  }

  /**
   * Throws {@code UnsupportedOperationException}.  Setting seeds in
   * this generator is not supported.
   *
   * @throws UnsupportedOperationException always
   */
  public void setSeed(long seed) {
    // only allow call from super() constructor
    if (initialized) {
      throw new UnsupportedOperationException();
    }
  }

  final long nextSeed() {
    Thread t;
    long r; // read and update per-thread seed
    UNSAFE.putLong(t = Thread.currentThread(), SEED,
        r = UNSAFE.getLong(t, SEED) + GAMMA);
    return r;
  }

  // We must define this, but never use it.
  protected int next(int bits) {
    return (int) (mix64(nextSeed()) >>> (64 - bits));
  }

  // IllegalArgumentException messages
  static final String BadBound = "bound must be positive";
  static final String BadRange = "bound must be greater than origin";
  static final String BadSize = "size must be non-negative";

  /**
   * The form of nextLong used by LongStream Spliterators.  If
   * origin is greater than bound, acts as unbounded form of
   * nextLong, else as bounded form.
   *
   * @param origin the least value, unless greater than bound
   * @param bound the upper bound (exclusive), must not equal origin
   * @return a pseudorandom value
   */
  final long internalNextLong(long origin, long bound) {
    long r = mix64(nextSeed());
    if (origin < bound) {
      long n = bound - origin, m = n - 1;
      if ((n & m) == 0L)  // power of two
      {
        r = (r & m) + origin;
      } else if (n > 0L) {  // reject over-represented candidates
        for (long u = r >>> 1;            // ensure nonnegative
            u + m - (r = u % n) < 0L;    // rejection check
            u = mix64(nextSeed()) >>> 1) // retry
        {
          ;
        }
        r += origin;
      } else {              // range not representable as long
        while (r < origin || r >= bound) {
          r = mix64(nextSeed());
        }
      }
    }
    return r;
  }

  /**
   * The form of nextInt used by IntStream Spliterators.
   * Exactly the same as long version, except for types.
   *
   * @param origin the least value, unless greater than bound
   * @param bound the upper bound (exclusive), must not equal origin
   * @return a pseudorandom value
   */
  final int internalNextInt(int origin, int bound) {
    int r = mix32(nextSeed());
    if (origin < bound) {
      int n = bound - origin, m = n - 1;
      if ((n & m) == 0) {
        r = (r & m) + origin;
      } else if (n > 0) {
        for (int u = r >>> 1;
            u + m - (r = u % n) < 0;
            u = mix32(nextSeed()) >>> 1) {
          ;
        }
        r += origin;
      } else {
        while (r < origin || r >= bound) {
          r = mix32(nextSeed());
        }
      }
    }
    return r;
  }

  /**
   * The form of nextDouble used by DoubleStream Spliterators.
   *
   * @param origin the least value, unless greater than bound
   * @param bound the upper bound (exclusive), must not equal origin
   * @return a pseudorandom value
   */
  final double internalNextDouble(double origin, double bound) {
    double r = (nextLong() >>> 11) * DOUBLE_UNIT;
    if (origin < bound) {
      r = r * (bound - origin) + origin;
      if (r >= bound) // correct for rounding
      {
        r = Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1);
      }
    }
    return r;
  }

  /**
   * Returns a pseudorandom {@code int} value.
   *
   * @return a pseudorandom {@code int} value
   */
  public int nextInt() {
    return mix32(nextSeed());
  }

  /**
   * Returns a pseudorandom {@code int} value between zero (inclusive)
   * and the specified bound (exclusive).
   *
   * @param bound the upper bound (exclusive).  Must be positive.
   * @return a pseudorandom {@code int} value between zero (inclusive) and the bound (exclusive)
   * @throws IllegalArgumentException if {@code bound} is not positive
   */
  public int nextInt(int bound) {
    if (bound <= 0) {
      throw new IllegalArgumentException(BadBound);
    }
    int r = mix32(nextSeed());
    int m = bound - 1;
    if ((bound & m) == 0) // power of two
    {
      r &= m;
    } else { // reject over-represented candidates
      for (int u = r >>> 1;
          u + m - (r = u % bound) < 0;
          u = mix32(nextSeed()) >>> 1) {
        ;
      }
    }
    return r;
  }

  /**
   * Returns a pseudorandom {@code int} value between the specified
   * origin (inclusive) and the specified bound (exclusive).
   *
   * @param origin the least value returned
   * @param bound the upper bound (exclusive)
   * @return a pseudorandom {@code int} value between the origin (inclusive) and the bound
   * (exclusive)
   * @throws IllegalArgumentException if {@code origin} is greater than or equal to {@code bound}
   */
  public int nextInt(int origin, int bound) {
    if (origin >= bound) {
      throw new IllegalArgumentException(BadRange);
    }
    return internalNextInt(origin, bound);
  }

  /**
   * Returns a pseudorandom {@code long} value.
   *
   * @return a pseudorandom {@code long} value
   */
  public long nextLong() {
    return mix64(nextSeed());
  }

  /**
   * Returns a pseudorandom {@code long} value between zero (inclusive)
   * and the specified bound (exclusive).
   *
   * @param bound the upper bound (exclusive).  Must be positive.
   * @return a pseudorandom {@code long} value between zero (inclusive) and the bound (exclusive)
   * @throws IllegalArgumentException if {@code bound} is not positive
   */
  public long nextLong(long bound) {
    if (bound <= 0) {
      throw new IllegalArgumentException(BadBound);
    }
    long r = mix64(nextSeed());
    long m = bound - 1;
    if ((bound & m) == 0L) // power of two
    {
      r &= m;
    } else { // reject over-represented candidates
      for (long u = r >>> 1;
          u + m - (r = u % bound) < 0L;
          u = mix64(nextSeed()) >>> 1) {
        ;
      }
    }
    return r;
  }

  /**
   * Returns a pseudorandom {@code long} value between the specified
   * origin (inclusive) and the specified bound (exclusive).
   *
   * @param origin the least value returned
   * @param bound the upper bound (exclusive)
   * @return a pseudorandom {@code long} value between the origin (inclusive) and the bound
   * (exclusive)
   * @throws IllegalArgumentException if {@code origin} is greater than or equal to {@code bound}
   */
  public long nextLong(long origin, long bound) {
    if (origin >= bound) {
      throw new IllegalArgumentException(BadRange);
    }
    return internalNextLong(origin, bound);
  }

  /**
   * Returns a pseudorandom {@code double} value between zero
   * (inclusive) and one (exclusive).
   *
   * @return a pseudorandom {@code double} value between zero (inclusive) and one (exclusive)
   */
  public double nextDouble() {
    return (mix64(nextSeed()) >>> 11) * DOUBLE_UNIT;
  }

  /**
   * Returns a pseudorandom {@code double} value between 0.0
   * (inclusive) and the specified bound (exclusive).
   *
   * @param bound the upper bound (exclusive).  Must be positive.
   * @return a pseudorandom {@code double} value between zero (inclusive) and the bound (exclusive)
   * @throws IllegalArgumentException if {@code bound} is not positive
   */
  public double nextDouble(double bound) {
    if (!(bound > 0.0)) {
      throw new IllegalArgumentException(BadBound);
    }
    double result = (mix64(nextSeed()) >>> 11) * DOUBLE_UNIT * bound;
    return (result < bound) ? result : // correct for rounding
        Double.longBitsToDouble(Double.doubleToLongBits(bound) - 1);
  }

  /**
   * Returns a pseudorandom {@code double} value between the specified
   * origin (inclusive) and bound (exclusive).
   *
   * @param origin the least value returned
   * @param bound the upper bound (exclusive)
   * @return a pseudorandom {@code double} value between the origin (inclusive) and the bound
   * (exclusive)
   * @throws IllegalArgumentException if {@code origin} is greater than or equal to {@code bound}
   */
  public double nextDouble(double origin, double bound) {
    if (!(origin < bound)) {
      throw new IllegalArgumentException(BadRange);
    }
    return internalNextDouble(origin, bound);
  }

  /**
   * Returns a pseudorandom {@code boolean} value.
   *
   * @return a pseudorandom {@code boolean} value
   */
  public boolean nextBoolean() {
    return mix32(nextSeed()) < 0;
  }

  /**
   * Returns a pseudorandom {@code float} value between zero
   * (inclusive) and one (exclusive).
   *
   * @return a pseudorandom {@code float} value between zero (inclusive) and one (exclusive)
   */
  public float nextFloat() {
    return (mix32(nextSeed()) >>> 8) * FLOAT_UNIT;
  }

  public double nextGaussian() {
    // Use nextLocalGaussian instead of nextGaussian field
    Double d = nextLocalGaussian.get();
    if (d != null) {
      nextLocalGaussian.set(null);
      return d.doubleValue();
    }
    double v1, v2, s;
    do {
      v1 = 2 * nextDouble() - 1; // between -1 and 1
      v2 = 2 * nextDouble() - 1; // between -1 and 1
      s = v1 * v1 + v2 * v2;
    } while (s >= 1 || s == 0);
    double multiplier = StrictMath.sqrt(-2 * StrictMath.log(s) / s);
    nextLocalGaussian.set(new Double(v2 * multiplier));
    return v1 * multiplier;
  }

  // stream methods, coded in a way intended to better isolate for
  // maintenance purposes the small differences across forms.

  /**
   * Returns a stream producing the given {@code streamSize} number of
   * pseudorandom {@code int} values.
   *
   * @param streamSize the number of values to generate
   * @return a stream of pseudorandom {@code int} values
   * @throws IllegalArgumentException if {@code streamSize} is less than zero
   * @since 1.8
   */
  public IntStream ints(long streamSize) {
    if (streamSize < 0L) {
      throw new IllegalArgumentException(BadSize);
    }
    return StreamSupport.intStream
        (new RandomIntsSpliterator
                (0L, streamSize, Integer.MAX_VALUE, 0),
            false);
  }

  /**
   * Returns an effectively unlimited stream of pseudorandom {@code int}
   * values.
   *
   * @return a stream of pseudorandom {@code int} values
   * @implNote This method is implemented to be equivalent to {@code ints(Long.MAX_VALUE)}.
   * @since 1.8
   */
  public IntStream ints() {
    return StreamSupport.intStream
        (new RandomIntsSpliterator
                (0L, Long.MAX_VALUE, Integer.MAX_VALUE, 0),
            false);
  }

  /**
   * Returns a stream producing the given {@code streamSize} number
   * of pseudorandom {@code int} values, each conforming to the given
   * origin (inclusive) and bound (exclusive).
   *
   * @param streamSize the number of values to generate
   * @param randomNumberOrigin the origin (inclusive) of each random value
   * @param randomNumberBound the bound (exclusive) of each random value
   * @return a stream of pseudorandom {@code int} values, each with the given origin (inclusive) and
   * bound (exclusive)
   * @throws IllegalArgumentException if {@code streamSize} is less than zero, or {@code
   * randomNumberOrigin} is greater than or equal to {@code randomNumberBound}
   * @since 1.8
   */
  public IntStream ints(long streamSize, int randomNumberOrigin,
      int randomNumberBound) {
    if (streamSize < 0L) {
      throw new IllegalArgumentException(BadSize);
    }
    if (randomNumberOrigin >= randomNumberBound) {
      throw new IllegalArgumentException(BadRange);
    }
    return StreamSupport.intStream
        (new RandomIntsSpliterator
                (0L, streamSize, randomNumberOrigin, randomNumberBound),
            false);
  }

  /**
   * Returns an effectively unlimited stream of pseudorandom {@code
   * int} values, each conforming to the given origin (inclusive) and bound
   * (exclusive).
   *
   * @param randomNumberOrigin the origin (inclusive) of each random value
   * @param randomNumberBound the bound (exclusive) of each random value
   * @return a stream of pseudorandom {@code int} values, each with the given origin (inclusive) and
   * bound (exclusive)
   * @throws IllegalArgumentException if {@code randomNumberOrigin} is greater than or equal to
   * {@code randomNumberBound}
   * @implNote This method is implemented to be equivalent to {@code ints(Long.MAX_VALUE,
   * randomNumberOrigin, randomNumberBound)}.
   * @since 1.8
   */
  public IntStream ints(int randomNumberOrigin, int randomNumberBound) {
    if (randomNumberOrigin >= randomNumberBound) {
      throw new IllegalArgumentException(BadRange);
    }
    return StreamSupport.intStream
        (new RandomIntsSpliterator
                (0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
            false);
  }

  /**
   * Returns a stream producing the given {@code streamSize} number of
   * pseudorandom {@code long} values.
   *
   * @param streamSize the number of values to generate
   * @return a stream of pseudorandom {@code long} values
   * @throws IllegalArgumentException if {@code streamSize} is less than zero
   * @since 1.8
   */
  public LongStream longs(long streamSize) {
    if (streamSize < 0L) {
      throw new IllegalArgumentException(BadSize);
    }
    return StreamSupport.longStream
        (new RandomLongsSpliterator
                (0L, streamSize, Long.MAX_VALUE, 0L),
            false);
  }

  /**
   * Returns an effectively unlimited stream of pseudorandom {@code long}
   * values.
   *
   * @return a stream of pseudorandom {@code long} values
   * @implNote This method is implemented to be equivalent to {@code longs(Long.MAX_VALUE)}.
   * @since 1.8
   */
  public LongStream longs() {
    return StreamSupport.longStream
        (new RandomLongsSpliterator
                (0L, Long.MAX_VALUE, Long.MAX_VALUE, 0L),
            false);
  }

  /**
   * Returns a stream producing the given {@code streamSize} number of
   * pseudorandom {@code long}, each conforming to the given origin
   * (inclusive) and bound (exclusive).
   *
   * @param streamSize the number of values to generate
   * @param randomNumberOrigin the origin (inclusive) of each random value
   * @param randomNumberBound the bound (exclusive) of each random value
   * @return a stream of pseudorandom {@code long} values, each with the given origin (inclusive)
   * and bound (exclusive)
   * @throws IllegalArgumentException if {@code streamSize} is less than zero, or {@code
   * randomNumberOrigin} is greater than or equal to {@code randomNumberBound}
   * @since 1.8
   */
  public LongStream longs(long streamSize, long randomNumberOrigin,
      long randomNumberBound) {
    if (streamSize < 0L) {
      throw new IllegalArgumentException(BadSize);
    }
    if (randomNumberOrigin >= randomNumberBound) {
      throw new IllegalArgumentException(BadRange);
    }
    return StreamSupport.longStream
        (new RandomLongsSpliterator
                (0L, streamSize, randomNumberOrigin, randomNumberBound),
            false);
  }

  /**
   * Returns an effectively unlimited stream of pseudorandom {@code
   * long} values, each conforming to the given origin (inclusive) and bound
   * (exclusive).
   *
   * @param randomNumberOrigin the origin (inclusive) of each random value
   * @param randomNumberBound the bound (exclusive) of each random value
   * @return a stream of pseudorandom {@code long} values, each with the given origin (inclusive)
   * and bound (exclusive)
   * @throws IllegalArgumentException if {@code randomNumberOrigin} is greater than or equal to
   * {@code randomNumberBound}
   * @implNote This method is implemented to be equivalent to {@code longs(Long.MAX_VALUE,
   * randomNumberOrigin, randomNumberBound)}.
   * @since 1.8
   */
  public LongStream longs(long randomNumberOrigin, long randomNumberBound) {
    if (randomNumberOrigin >= randomNumberBound) {
      throw new IllegalArgumentException(BadRange);
    }
    return StreamSupport.longStream
        (new RandomLongsSpliterator
                (0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
            false);
  }

  /**
   * Returns a stream producing the given {@code streamSize} number of
   * pseudorandom {@code double} values, each between zero
   * (inclusive) and one (exclusive).
   *
   * @param streamSize the number of values to generate
   * @return a stream of {@code double} values
   * @throws IllegalArgumentException if {@code streamSize} is less than zero
   * @since 1.8
   */
  public DoubleStream doubles(long streamSize) {
    if (streamSize < 0L) {
      throw new IllegalArgumentException(BadSize);
    }
    return StreamSupport.doubleStream
        (new RandomDoublesSpliterator
                (0L, streamSize, Double.MAX_VALUE, 0.0),
            false);
  }

  /**
   * Returns an effectively unlimited stream of pseudorandom {@code
   * double} values, each between zero (inclusive) and one
   * (exclusive).
   *
   * @return a stream of pseudorandom {@code double} values
   * @implNote This method is implemented to be equivalent to {@code doubles(Long.MAX_VALUE)}.
   * @since 1.8
   */
  public DoubleStream doubles() {
    return StreamSupport.doubleStream
        (new RandomDoublesSpliterator
                (0L, Long.MAX_VALUE, Double.MAX_VALUE, 0.0),
            false);
  }

  /**
   * Returns a stream producing the given {@code streamSize} number of
   * pseudorandom {@code double} values, each conforming to the given origin
   * (inclusive) and bound (exclusive).
   *
   * @param streamSize the number of values to generate
   * @param randomNumberOrigin the origin (inclusive) of each random value
   * @param randomNumberBound the bound (exclusive) of each random value
   * @return a stream of pseudorandom {@code double} values, each with the given origin (inclusive)
   * and bound (exclusive)
   * @throws IllegalArgumentException if {@code streamSize} is less than zero
   * @throws IllegalArgumentException if {@code randomNumberOrigin} is greater than or equal to
   * {@code randomNumberBound}
   * @since 1.8
   */
  public DoubleStream doubles(long streamSize, double randomNumberOrigin,
      double randomNumberBound) {
    if (streamSize < 0L) {
      throw new IllegalArgumentException(BadSize);
    }
    if (!(randomNumberOrigin < randomNumberBound)) {
      throw new IllegalArgumentException(BadRange);
    }
    return StreamSupport.doubleStream
        (new RandomDoublesSpliterator
                (0L, streamSize, randomNumberOrigin, randomNumberBound),
            false);
  }

  /**
   * Returns an effectively unlimited stream of pseudorandom {@code
   * double} values, each conforming to the given origin (inclusive) and bound
   * (exclusive).
   *
   * @param randomNumberOrigin the origin (inclusive) of each random value
   * @param randomNumberBound the bound (exclusive) of each random value
   * @return a stream of pseudorandom {@code double} values, each with the given origin (inclusive)
   * and bound (exclusive)
   * @throws IllegalArgumentException if {@code randomNumberOrigin} is greater than or equal to
   * {@code randomNumberBound}
   * @implNote This method is implemented to be equivalent to {@code doubles(Long.MAX_VALUE,
   * randomNumberOrigin, randomNumberBound)}.
   * @since 1.8
   */
  public DoubleStream doubles(double randomNumberOrigin, double randomNumberBound) {
    if (!(randomNumberOrigin < randomNumberBound)) {
      throw new IllegalArgumentException(BadRange);
    }
    return StreamSupport.doubleStream
        (new RandomDoublesSpliterator
                (0L, Long.MAX_VALUE, randomNumberOrigin, randomNumberBound),
            false);
  }

  /**
   * Spliterator for int streams.  We multiplex the four int
   * versions into one class by treating a bound less than origin as
   * unbounded, and also by treating "infinite" as equivalent to
   * Long.MAX_VALUE. For splits, it uses the standard divide-by-two
   * approach. The long and double versions of this class are
   * identical except for types.
   */
  static final class RandomIntsSpliterator implements Spliterator.OfInt {

    long index;
    final long fence;
    final int origin;
    final int bound;

    RandomIntsSpliterator(long index, long fence,
        int origin, int bound) {
      this.index = index;
      this.fence = fence;
      this.origin = origin;
      this.bound = bound;
    }

    public RandomIntsSpliterator trySplit() {
      long i = index, m = (i + fence) >>> 1;
      return (m <= i) ? null :
          new RandomIntsSpliterator(i, index = m, origin, bound);
    }

    public long estimateSize() {
      return fence - index;
    }

    public int characteristics() {
      return (Spliterator.SIZED | Spliterator.SUBSIZED |
          Spliterator.NONNULL | Spliterator.IMMUTABLE);
    }

    public boolean tryAdvance(IntConsumer consumer) {
      if (consumer == null) {
        throw new NullPointerException();
      }
      long i = index, f = fence;
      if (i < f) {
        consumer.accept(ThreadLocalRandom.current().internalNextInt(origin, bound));
        index = i + 1;
        return true;
      }
      return false;
    }

    public void forEachRemaining(IntConsumer consumer) {
      if (consumer == null) {
        throw new NullPointerException();
      }
      long i = index, f = fence;
      if (i < f) {
        index = f;
        int o = origin, b = bound;
        ThreadLocalRandom rng = ThreadLocalRandom.current();
        do {
          consumer.accept(rng.internalNextInt(o, b));
        } while (++i < f);
      }
    }
  }

  /**
   * Spliterator for long streams.
   */
  static final class RandomLongsSpliterator implements Spliterator.OfLong {

    long index;
    final long fence;
    final long origin;
    final long bound;

    RandomLongsSpliterator(long index, long fence,
        long origin, long bound) {
      this.index = index;
      this.fence = fence;
      this.origin = origin;
      this.bound = bound;
    }

    public RandomLongsSpliterator trySplit() {
      long i = index, m = (i + fence) >>> 1;
      return (m <= i) ? null :
          new RandomLongsSpliterator(i, index = m, origin, bound);
    }

    public long estimateSize() {
      return fence - index;
    }

    public int characteristics() {
      return (Spliterator.SIZED | Spliterator.SUBSIZED |
          Spliterator.NONNULL | Spliterator.IMMUTABLE);
    }

    public boolean tryAdvance(LongConsumer consumer) {
      if (consumer == null) {
        throw new NullPointerException();
      }
      long i = index, f = fence;
      if (i < f) {
        consumer.accept(ThreadLocalRandom.current().internalNextLong(origin, bound));
        index = i + 1;
        return true;
      }
      return false;
    }

    public void forEachRemaining(LongConsumer consumer) {
      if (consumer == null) {
        throw new NullPointerException();
      }
      long i = index, f = fence;
      if (i < f) {
        index = f;
        long o = origin, b = bound;
        ThreadLocalRandom rng = ThreadLocalRandom.current();
        do {
          consumer.accept(rng.internalNextLong(o, b));
        } while (++i < f);
      }
    }

  }

  /**
   * Spliterator for double streams.
   */
  static final class RandomDoublesSpliterator implements Spliterator.OfDouble {

    long index;
    final long fence;
    final double origin;
    final double bound;

    RandomDoublesSpliterator(long index, long fence,
        double origin, double bound) {
      this.index = index;
      this.fence = fence;
      this.origin = origin;
      this.bound = bound;
    }

    public RandomDoublesSpliterator trySplit() {
      long i = index, m = (i + fence) >>> 1;
      return (m <= i) ? null :
          new RandomDoublesSpliterator(i, index = m, origin, bound);
    }

    public long estimateSize() {
      return fence - index;
    }

    public int characteristics() {
      return (Spliterator.SIZED | Spliterator.SUBSIZED |
          Spliterator.NONNULL | Spliterator.IMMUTABLE);
    }

    public boolean tryAdvance(DoubleConsumer consumer) {
      if (consumer == null) {
        throw new NullPointerException();
      }
      long i = index, f = fence;
      if (i < f) {
        consumer.accept(ThreadLocalRandom.current().internalNextDouble(origin, bound));
        index = i + 1;
        return true;
      }
      return false;
    }

    public void forEachRemaining(DoubleConsumer consumer) {
      if (consumer == null) {
        throw new NullPointerException();
      }
      long i = index, f = fence;
      if (i < f) {
        index = f;
        double o = origin, b = bound;
        ThreadLocalRandom rng = ThreadLocalRandom.current();
        do {
          consumer.accept(rng.internalNextDouble(o, b));
        } while (++i < f);
      }
    }
  }

  // Within-package utilities

    /*
     * Descriptions of the usages of the methods below can be found in
     * the classes that use them. Briefly, a thread's "probe" value is
     * a non-zero hash code that (probably) does not collide with
     * other existing threads with respect to any power of two
     * collision space. When it does collide, it is pseudo-randomly
     * adjusted (using a Marsaglia XorShift). The nextSecondarySeed
     * method is used in the same contexts as ThreadLocalRandom, but
     * only for transient usages such as random adaptive spin/block
     * sequences for which a cheap RNG suffices and for which it could
     * in principle disrupt user-visible statistical properties of the
     * main ThreadLocalRandom if we were to use it.
     *
     * Note: Because of package-protection issues, versions of some
     * these methods also appear in some subpackage classes.
     */

  /**
   * Returns the probe value for the current thread without forcing
   * initialization. Note that invoking ThreadLocalRandom.current()
   * can be used to force initialization on zero return.
   */
  static final int getProbe() {
    return UNSAFE.getInt(Thread.currentThread(), PROBE);
  }

  /**
   * Pseudo-randomly advances and records the given probe value for the
   * given thread.
   */
  static final int advanceProbe(int probe) {
    probe ^= probe << 13;   // xorshift
    probe ^= probe >>> 17;
    probe ^= probe << 5;
    UNSAFE.putInt(Thread.currentThread(), PROBE, probe);
    return probe;
  }

  /**
   * Returns the pseudo-randomly initialized or updated secondary seed.
   */
  static final int nextSecondarySeed() {
    int r;
    Thread t = Thread.currentThread();
    if ((r = UNSAFE.getInt(t, SECONDARY)) != 0) {
      r ^= r << 13;   // xorshift
      r ^= r >>> 17;
      r ^= r << 5;
    } else {
      localInit();
      if ((r = (int) UNSAFE.getLong(t, SEED)) == 0) {
        r = 1; // avoid zero
      }
    }
    UNSAFE.putInt(t, SECONDARY, r);
    return r;
  }

  // Serialization support

  private static final long serialVersionUID = -5851777807851030925L;

  /**
   * @serialField rnd long seed for random computations
   * @serialField initialized boolean always true
   */
  private static final ObjectStreamField[] serialPersistentFields = {
      new ObjectStreamField("rnd", long.class),
      new ObjectStreamField("initialized", boolean.class),
  };

  /**
   * Saves the {@code ThreadLocalRandom} to a stream (that is, serializes it).
   *
   * @param s the stream
   * @throws java.io.IOException if an I/O error occurs
   */
  private void writeObject(java.io.ObjectOutputStream s)
      throws java.io.IOException {

    java.io.ObjectOutputStream.PutField fields = s.putFields();
    fields.put("rnd", UNSAFE.getLong(Thread.currentThread(), SEED));
    fields.put("initialized", true);
    s.writeFields();
  }

  /**
   * Returns the {@link #current() current} thread's {@code ThreadLocalRandom}.
   *
   * @return the {@link #current() current} thread's {@code ThreadLocalRandom}
   */
  private Object readResolve() {
    return current();
  }

  // Unsafe mechanics
  private static final sun.misc.Unsafe UNSAFE;
  private static final long SEED;
  private static final long PROBE;
  private static final long SECONDARY;

  static {
    try {
      UNSAFE = sun.misc.Unsafe.getUnsafe();
      Class<?> tk = Thread.class;
      SEED = UNSAFE.objectFieldOffset
          (tk.getDeclaredField("threadLocalRandomSeed"));
      PROBE = UNSAFE.objectFieldOffset
          (tk.getDeclaredField("threadLocalRandomProbe"));
      SECONDARY = UNSAFE.objectFieldOffset
          (tk.getDeclaredField("threadLocalRandomSecondarySeed"));
    } catch (Exception e) {
      throw new Error(e);
    }
  }
}
